This project will use newly developed quantitative proteomic methodology to provide insights into protein:protein interactions relevant to hemolytic anemia. Fundamental questions remain unanswered surrounding the clinical variability and non-erythroid effects of known RBC membrane skeleton mutations. Past RBC analysis has been hampered by the complexity of the system and limitations in detecting low abundance proteins. Proteomic technology offers a less biased approach to globally profile RBC protein Interactions. Preparations of RBC ghosts from healthy mice and from mouse models of hemolytic anemia will be analyzed by tandem mass spectrometry. These analyses will help define a core set of proteins for the normal RBC that can be compared with the profile for diseased RBCs. It is hypothesized that alterations in the structure and or abundance of specific proteins will represent candidates that may be involved in disease severity and pathophysiology in non-erythroid cells. We hope that a deeper understanding of protein-protein interactions within the RBC can provide new insights into inherited hemolytic anemia.